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基于长短锚杆组合支护理论,提出了一种隧道径向锚钉-斜交锚杆复合支护技术,该技术可提高支护结构的整体抗力,有利于缩小围岩塑性区半径,增加锚杆处于稳定围岩区的长度。为进一步研究锚钉和锚杆的组合长度,将隧道围岩划分为A、B和C三区,并把锚杆作用在围岩体内的剪应力简化为环向边界应力,运用厚壁圆筒弹塑性理论推导了锚钉和锚杆组合长度计算式。实例分析表明,0.8m(锚钉)和3.8m(锚杆)的组合长度可以使隧道塑性区半径降低28%,锚固盲区减小88.8%。可见,在隧道长短锚杆组合支护理论中,该计算方法对围岩锚固体长度参数设计有一定指导意义。
Based on the combined support theory of long and short rock bolts, a radial support bolt-skew anchor composite support technology is proposed, which can improve the overall resistance of the support structure, reduce the plastic zone radius of surrounding rock and increase the anchorage Rod in a stable rock area length. In order to further study the combined length of anchor bolt and anchor rod, the surrounding rock of tunnel is divided into three zones A, B and C, and the shear stress acting in the surrounding rock mass is reduced to the circumferential boundary stress. Elastic-plastic theory deduced the anchor bolt and bolt combination length calculation formula. The case study shows that the combined length of 0.8m (anchor bolt) and 3.8m (bolt) can reduce the tunnel plastic zone radius by 28% and the anchor blind zone by 88.8%. It can be seen that this calculation method is of guiding significance to the design of the length parameter of rock mass in the tunnel.